This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our fascination is with structure and molecular dynamics of vaccinia virus poly(A) polymerase (VP55) - the only non-templated RNA polymerase known to translocate with respect to its RNA primer. It has a processivity factor (VP39) that changes the mode of translocation. Past, collaborative studies yielded a crystal structure for VP55 complexed with VP39. Currently, the most important, yet incomplete structural information regards the VP55-VP39-RNA complex. Soaking of well characterized crystals with short RNA segments and ATP has recently provided exciting preliminary data. However, our current, lower resolution (3.36 [unreadable]) hinders our full understanding of the mechanism of polyadenylation, in this competitive field. We very much need just a little higher resolution to fully resolve the catalytic complex with primer and NTP.